The invention relates to an arrangement for protecting against the incorrect plugging of plug-in modules on the front and rear side of a backplane, comprising at least one pair of guide pin elements with guide pins pointing in opposite directions which extend along a common longitudinal axis perpendicularly to the backplane and engage positively in corresponding guide receptacles of the plug-in modules when they are plugged on the correct way around, and means for non-rotatably mounting the guide pin elements on the front and rear side of the backplane in a predetermined angular position.
Such arrangements are used, among other things, in 19″ rack mount systems and in AIR Transition Racks (ATR) and ensure, for example, that electrical plug-in assemblies can only be plugged in the correct position onto slots on the backplane.
U.S. Pat. No. 6,945,810 B1 describes an arrangement with guide pins that are embodied as one-piece elements. Between the two ends, the guide pins have a mounting area that is bounded on one side by an offset. The attachment area enables the non-rotatable attachment of the guide pin on the backplane. For this purpose, the guide pin is plugged in a positive manner into a through hole in the backplane. While the offset lies against one side of the backplane, a nut is screwed onto the guide pin on the opposite side of the backplane in order to attach the guide pin to the backplane. Both ends of the guide pin have coding surfaces that engage into corresponding receptacles on the plug-in modules or plug-in assemblies. The position of the coding surfaces relative to each other cannot be changed, which represents a limitation.
EP 1 753 281 B1 describes a multipart guide pin comprising a first and a second guide pin element which are plugged into a through hole in a backplane from mutually opposing sides. The first guide pin element has a through hole through which an attachment element engages into a threaded hole in the second guide pin element, thus fixing the two guide pin elements to the backplane. At the opposing ends, the guide pin elements each have a rib that engages into a radial recess in the hole of the backplane. Both ribs can engage either in a common radial recess or in two separate recesses. Each of the two guide pin elements has a coding surface that engages into corresponding receptacles of the plug-in modules when they are plugged onto the guide pin elements. If the ribs engage into a single recess in the hole of the backplane, the coding surfaces are aligned parallel in relation to each other. If the ribs are arranged in radially different recesses, the coding surfaces are rotated in relation to each other. The manufacture of such a guide pin arrangement, particularly of the guide pin elements, is elaborate, and assembly is laborious.